Loading Files

Whim can compile and run another source file while a program runs.

require!

require!($path) resolves the path, compiles the file, links its symbols, and runs its file-scope statements:

require!(directory!() . '/support.whim');

directory!() returns the directory of the current source file. Use it for a path that should not depend on the process working directory.

A source file returns null. A parse, compile, link, or file error throws. A symbol declared by a successful load becomes available to later code.

require! runs the file each time. A file that declares symbols cannot usually run twice because the second load would redeclare them.

require_once!

require_once!($path) loads a resolved path at most once:

require_once!(directory!() . '/vendor/autoload.whim');

A later call for the same resolved path returns null without running the file again. Circular require_once! calls stop when they reach a file whose load has started but not ended.

If require! loaded a path first, require_once! also treats it as loaded.

Compile and link order

Whim compiles a loaded file as one unit. Declarations in that unit can refer to each other even when the source declares them later.

The linker rejects duplicate names before it publishes the new unit. A failed load does not replace an existing symbol.

Autoloading

When Whim needs an unknown symbol, it may ask registered autoloaders to define it. Type checks, generic arguments, property types, constants, and ordinary calls may all trigger autoloading.

An autoloader must return true only after it has defined the requested symbol. See Autoloading for the API and generated Git dependency loader.